Terahertz (THz) radiation has a wide range of useful applications, many of which would benefit from a compact THz radiation source capable of operating at room temperature and in continuous-wave mode. Unfortunately, currently available THz sources are typically bulky, involve complex architectures and operate at low temperatures or in vacuum.
The two architectures that have arguably shown the most promise for the fabrication of compact, solid-state semiconductor based THz sources are quantum cascade (QC) architectures and CMOS-compatible oscillators connected in a ring architecture. However, the multilayer structures in a QC architecture are generally microns thick and, therefore, are not amenable to stretching and deformation.
In a CMOS oscillator-based source, THz frequencies are obtained by coupling several oscillators in a ring using a set of complex circuits. The oscillators lock-in at equilibrium at a certain frequency. The topology of the ring and the circuits connecting the oscillators can be designed to obtain the desired radiation frequency. Providing tunable frequencies and power in such devices requires including more oscillators in the ring, fabricating multiple rings, or modifying the circuits interconnecting the oscillators. This results in an increase in complexity and occupied area on-chip.